The present invention relates generally to gas generating systems and, more particularly, to gas generating systems for use in applications such as inflatable occupant restraint systems in motor vehicles.
Gas generating systems used for deploying an air bag in a motor vehicle generally employ a single gas generator in fluid communication with an uninflated air bag. The gas generator is typically triggered by a firing circuit when the sensed vehicle acceleration exceeds a predetermined threshold value, as through the use of an acceleration-responsive inertial switch.
An ongoing challenge is to improve the kinematics of the occupant during a crash event by tailoring the onset/pressurization inflation rate of the airbag. To that end, dual or multiple chamber inflators have been developed.
For example, a gas generating system may include two chambers in a single housing defined by a mechanically retained wall or barrier between the ends thereof. Each chamber is of a predetermined size that is determinative of the propellant capacity and consequently, of the inflating capability of the chamber. Upon the occurrence of a vehicle collision, depending on the weight of the passenger, either chamber or both chambers may be selectively ignited thereby inflating the protective airbag. However, it is important to ensure that the wall remains in position within the housing when only one chamber is fired.
It is also important to efficiently cool and filter generated gases prior to their diffusion into an associated airbag or other inflatable device.
In addition, in gas generating systems using elongated housings, proper alignment and securement of concentric longitudinal components within the housing during assembly can be time-consuming.
Therefore, a need exists for an easily manufacturable multi-chamber gas generating system which provides adequate cooling of generated gases prior to disbursement, and which can produce selective air bag inflation pressurization yet prevent hazardous structural failure of the gas generator.